package com.lujian.casual.benchmark;

import org.openjdk.jmh.annotations.*;
import org.openjdk.jmh.runner.Runner;
import org.openjdk.jmh.runner.RunnerException;
import org.openjdk.jmh.runner.options.Options;
import org.openjdk.jmh.runner.options.OptionsBuilder;

import java.util.ArrayList;
import java.util.LinkedList;
import java.util.List;
import java.util.Queue;
import java.util.concurrent.TimeUnit;


@BenchmarkMode(Mode.AverageTime)
@OutputTimeUnit(TimeUnit.NANOSECONDS)
@Warmup(iterations = 5, time = 1, timeUnit = TimeUnit.SECONDS)
@Measurement(iterations = 5, time = 1, timeUnit = TimeUnit.SECONDS)
@Fork(1)
@State(Scope.Thread)
public class BenchMarkStateDAG {


        /**
         * WARNING:
         * THIS IS AN EXPERIMENTAL FEATURE, BE READY FOR IT BECOME REMOVED WITHOUT NOTICE!
         */

        /**
         * There are weird cases when the benchmark state is more cleanly described
         * by the set of @States, and those @States reference each other. JMH allows
         * linking @States in directed acyclic graphs (DAGs) by referencing @States
         * in helper method signatures. (Note that black hole helps)
         * is just a special case of that.
         *
         * Following the interface for @Benchmark calls, all @Setups for
         * referenced @State-s are fired before it becomes accessible to current @State.
         * Similarly, no @TearDown methods are fired for referenced @State before
         * current @State is done with it.
         */

    /*
     * This is a model case, and it might not be a good benchmark.
     * // TODO: Replace it with the benchmark which does something useful.
     */

        public static class Counter {
            int x;

            public int inc() {
                return x++;
            }

            public void dispose() {
                // pretend this is something really useful
            }
        }

    /*
     * Shared state maintains the set of Counters, and worker threads should
     * poll their own instances of Counter to work with. However, it should only
     * be done once, and therefore, Local state caches it after requesting the
     * counter from Shared state.
     */

        @State(Scope.Benchmark)
        public static class Shared {
            List<Counter> all;
            Queue<Counter> available;

            @Setup
            public synchronized void setup() {
                all = new ArrayList<>();
                for (int c = 0; c < 10; c++) {
                    all.add(new Counter());
                }

                available = new LinkedList<>();
                available.addAll(all);
            }

            @TearDown
            public synchronized void tearDown() {
                for (Counter c : all) {
                    c.dispose();
                }
            }

            public synchronized Counter getMine() {
                return available.poll();
            }
        }

        @State(Scope.Thread)
        public static class Local {
            Counter cnt;

            @Setup
            public void setup(Shared shared) {
                cnt = shared.getMine();
            }
        }

        @Benchmark
        public int test(Local local) {
            return local.cnt.inc();
        }

    /*
     * ============================== HOW TO RUN THIS TEST: ====================================
     *
     * You can run this test:
     *
     * a) Via the command line:
     *    $ mvn clean install
     *    $ java -jar target/benchmarks.jar JMHSample_29
     *
     * b) Via the Java API:
     *    (see the JMH homepage for possible caveats when running from IDE:
     *      http://openjdk.java.net/projects/code-tools/jmh/)
     */

        public static void main(String[] args) throws RunnerException {
            Options opt = new OptionsBuilder()
                    .include(BenchMarkStateDAG.class.getSimpleName())
                    .build();

            new Runner(opt).run();
        }


}
